1. Field of the Invention
The invention relates to a method and apparatus for applying photo-luminescent pigment to a substrate surface, more particularly for applying photo-luminescent pigment to aluminum or other metal strips used, for example, as stair nosings. The invention also relates to a product produced by said method and apparatus.
2. Background to the Invention
Low level floor or walkway lighting is commonly used in such places as picture theaters, sports arenas and aircraft as both a courtesy and safety feature for patrons or passengers. This lighting often takes the form of an electrical or electronic lighting means in or on the floor along either side of a walkway or across the nosing of stairs. Low level floor lighting is particularly important in picture theaters and sports arenas where patrons may be required to negotiate steps in aisles when only low levels of ambient light are present, or in stairwells of buildings during an emergency when there may be failure of the main lighting source.
Known methods of floor lighting using electrical or electronic means have a disadvantage because they require electrical wiring to be run to areas where access for the wiring may be limited. They are also prone to failure during failure of the main power supply. Additionally, the electronic lighting means are often of a low voltage type requiring some form of voltage reduction means such as an inverter, converter, or transformer. Not only does addition of this equipment add to the complexity and cost of the installation but also provides for additional modes of failure.
It is known to apply a photo-luminescent pigment to a rope, tape or fabric. This photo-luminescent pigment is stimulated by visible light and remains luminescent for a considerable period after the light source is removed. The problem with tape or fabric impregnated with pigment is that lacks durability for heavy wear areas such as walkways or stairs.
Photo-luminescent pigment has been sprayed onto more durable substrate surfaces such as aluminum or metal strips or extrusions. Once the spray has dried, it is ground to provide a smooth finished surface. This overcomes the abovementioned problems associated with heavy wear areas, but considerable pigment is wasted during the spraying and grinding process.
Accordingly it is an object of the present invention to provide a method and apparatus for applying photo-luminescence pigment to a substrate which avoids or overcomes some of the abovementioned disadvantages, or which at least provides the public with a useful choice.
According to a first aspect of the invention there is provided a method of applying photo-luminescent pigment to a substrate, said method including:
preparing a dry powder formulation comprising, at least, a photo-luminescent pigment and a carrier/fixer;
depositing the dry powder formulation onto a substrate surface;
heating the dry powder formulation to fuse it to the substrate surface.
Preferably the substrate surface has depressions or channels adapted to receive the dry powder formulation.
Preferably a light reflecting layer is applied to the substrate surface before depositing the dry powder formulation.
Preferably the volume ratio of photo-luminescent pigment to carrier/fixer in the dry powder formulation is such that the fused material exhibits substantially the same strength and durability properties of the carrier/fixer, while still exhibiting the photo-luminescent properties of the pigment. More preferably the volume ratio is substantially in the range of 1% to 35% photo-luminescent pigment to carrier/fixer.
Preferably the dry powered formulation may be heated to between, substantially, 160 to 210 degrees centigrade, or to a temperature recommended by the manufacturer of the carrier/fixer, for approximately 10 to 20 minutes or until the formulation is molten. The molten formulation may be cooled after heating.
Preferably the carrier/fixer is a heat curable polymer.
Preferably the dry powder formulation may include small quantities of additives, such as a de-gassing additive, to ensure a smooth surface finish.
Preferably the substrate is stamped, extruded or milled aluminum or metal.
According to a second aspect of the invention there is provided an apparatus for applying photo-luminescent pigment to a substrate, said apparatus including:
a hopper adapted to contain a dry powder formulation;
one or more orifices adapted to allow transfer of the dry powder formulation from the hopper to a substrate surface;
a guide rail system for locating the substrate surface in both a fixed horizontal plane and a fixed vertical plane below the hopper and orifice; and
a heat-curing system for providing enough heat to turn the dry powder formulation into a molten mix.
Preferably the apparatus also includes a cooling system to cool the molten mix.
Preferably the apparatus also includes a drive system to move the substrate through the apparatus.
Preferably the apparatus includes a support roller mounted directly beneath the orifice(s) and hopper to support the substrate.
Preferably the apparatus includes an adjustable mounting bracket adapted to enable the hopper to be located in the correct position so that the orifice(s) lines up with the substrate.
Preferably the orifice is adapted to communicate snugly with the substrate surface such that the dry powder formulation is deposited substantially only where required.
Preferably the apparatus includes a mechanism for tapping or shaking the hopper so that any voids in the dry powder formulation are re-filled.
Preferably the apparatus includes a brush mounted below the roller, and with its bristles in contact with the roller, so that any powder that falls onto the roller is subsequently brushed off.
The heat-curing system may be an oven. Optionally, the heat-curing system may be a continuous oven process, and in one embodiment may include infra-red heating elements.
Preferably the apparatus includes an automatic loading and unloading means at each end thereof.
The invention also provides for a product when produced according to the process, or by an apparatus, herebefore defined.
Further aspects of the invention will become apparent from the following description which is given by way of example only.